Gas turbine engines, such as those utilized in commercial and military aircraft, include a compressor section that compresses air, a combustor section in which the compressed air is mixed with a fuel and ignited, and a turbine section across which the resultant combustion products are expanded. The expansion of the combustion products drives the turbine section to rotate. As the turbine section is connected to the compressor section via a shaft, the rotation of the turbine section further drives the compressor section to rotate. A fan is also connected to the shaft and is driven to rotate via rotation of the turbine as well.
In some alternative engines, alternative sources of compressed air can be utilized, with the alternative sources being referred to as gas generators. The alternative engines can include the gas generators in line with the combustor and the turbine section, or out of line with the turbine section, depending on the needs of the aircraft incorporating the particular engine.
Rotation of the fan causes the tips of the fan blades to travel at a substantially faster speed than the primary body portions of the fan blades, resulting in greater levels of air ingestion at the blade tip portion than at the body portion of the fan blade. This, in turn, can result in unsteady loading due to inlet distortion of the fan blades.